MONDAY, March 16, 2026 (HealthDay News) -- Interim influenza vaccine effectiveness for the 2025 to 2026 season appears to be lower than in recent influenza seasons, but still provides protection for children and adolescents and for adults, according to research published in the March 12 issue of the U.S. Centers for Disease Control and Prevention Morbidity and Mortality Weekly Report.
Patrick Maloney, Ph.D., from the CDC in Atlanta, and colleagues calculated interim influenza vaccine effectiveness (VE) estimates for patients with acute respiratory illness-associated outpatient visits and hospitalizations from three U.S. respiratory virus VE networks during the 2025 to 2026 influenza season.
The researchers found that VE was 38 to 41 percent against influenza outpatient visits and 41 percent against influenza-associated hospitalization among children and adolescents aged younger than 18 years. The corresponding VE among adults aged 18 years and older was 22 to 34 percent against influenza outpatient visits and 30 percent against influenza-associated hospitalization. VE against influenza A varied from 37 percent against outpatient visits to 42 percent against hospitalization across settings among children and adolescents, and from 30 percent against hospitalization to 34 percent against outpatient visits across settings for adults. VE against influenza A(H3N2)-associated outpatient visits and hospitalization was 35 and 38 percent, respectively, among children and adolescents. VE against influenza B outpatient visits was 63 percent among adults and varied from 45 to 71 percent among children and adolescents.
"Even in seasons when overall VE is reduced, influenza vaccination has prevented thousands of hospitalizations and deaths," the authors write.